Method and apparatus for making bearings



Dec. 31, 1968 c. 5. WHITE METHOD AND APPARATUS FOR MAKING BEARINGS FiledSept. 25, 1967 Sheet 1 of.5 1H"! A Q i6 9 2 1 ,1. .nill il 4 1 50LiiEiimI q uuu' gr! W 917 all/W INVENTOR.

Dec. 31, 1968 c. s. WHITE 3,418,706

METHOD AND APPARATUS FOR MAKING BEARINGS Filed Sept. 25, 1967 Sheet 2 of5 fiz.

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INVENTOR. L Chunk; 5. W/u'fe BY Dec. 31, 1968 c. 5. WHITE METHOD ANDAPPARATUS FOR MAKING BEARINGS Filed Sept. 25, 1967 Sheet 3 of INVENTOR.Y (Farr/e; .5. 11%;? B fi al?! 14 TTOK/Vf United States Patent 03,418,706 METHOD AND APPARATUS FOR MAKING BEARINGS Charles S. White,35826 41st St., Palmdale, Calif. 93550 Continuation-impart of abandonedapplication Ser. No.

472,956, July 19, 1965. This appiication Sept. 25, 1967,

Ser. No. 676,909

31 Claims. (Ci. 29149.5)

ABSTRACT OF THE DISCLOSURE In accordance with the invention, lowfriction bearings are manufactured by wrapping around a curved membersuch as a shaft or a ball, a metal strip preferably having a lowfriction facing and having complementary locking means at the oppositeends thereof. T he locking means are locked together to form an annulusaround the shaft or ball as the final step in the wrapping operation. Inthe preferred embodiment the central portion of the strip is first bentinto conformity with the shaft or ball after which one end of the stripand then the other end are wrapped against the shaft or ball. Toaccomplish this, the apparatus has a plurality of die members whichfunction in sequence to contact the various portions of the strip andwrap them against the shaft or ball in the order described. A longlength of strip can be fed to the apparatus and cut to proper length,with the locking means formed therein, by the apparatus just prior tothe wrappin g operation. Hence, self lubricating bushings, ball jointsand similar bearings can be rapidly manufactured to close tolerances andat low cost.

This invention relates to a method and apparatus for manufacturingannular bearings or the like. '1' iis application is acontinuation-in-part of application Ser. No. 472,956 filed July 19,1965, now abandoned.

Bearings for many types of applications are in the form of an annularelement disposed about a shaft or ball to allow sliding movement, theelement being disposed within another member which supports the shaft orball. The inner shaft or ball is permitted movement relative to theouter structure for whatever purpose may be desired. Such bearings mustbe precisely manufactured, both as to dimension and shape, in order toproperly support the inner member relative to the outer member and toallow low friction movement of one of the members relative to the other.

Numerous methods for making such annular bearings are well known in theprior art. However, most of these methods are costly and cumbersome,requiring a large number of operations and requiring extreme precisionin the machinery and methods. For example, one method of forming abearing to be received over a truncated spherical ball in the typicalrod end universal joint or the like, is to place such spherical ball ina suitable swaging die having spherical die cavities, placing aprecisely formed cylindrical ring in proper position around thespherical ball, and then moving the swaging dies together so as toconform the ring to the outer surface of the ball. Due to the sphericalshape of the swaging dies required to accomplish this result, theresultant assembly must be further machined an ground before it can beinstalled within an outer rod end member or the like Where it is to beaffixed. An operation such as this is time consuming and expensive, anddoes not admit of progressive or automated formation of bearing membersin an economical and efiicient manner.

The method and apparatus of this invention enables forming annularbearing elements in such a way that permits progressive and high speedformation without 3,418,706 Patented Dec. 31, 1968 ice sacrificingprecision dimensions or shape in the finished bearing element. Themethod contemplates a mandrel received and supported in a machine havingan upper forming die, and first and second lower forming dies. A bearingblank, which can comprise a strip of metal sheet stock, is disposedbetween the mandrel and the upper forming die, the blank being providedwith complementary locking means on the opposite ends thereof. The blankis partially formed around the mandrel by the upper forming die and thefirst lower forming die forms one end of the blank around the mandrel.Following this operation, the second lower forming die forms theopposite end of the blank around the mandrel, and in such a way as tointerlock the locking means to secure the ends of the blank together andto maintain the bearing element in an annular shape. Following theseoperations, the mandrel may be indexed and a new blank formed around themandrel in the same manner. After a plurality of complete cycles, themandrel will have a plurality of spaced bearing members formed thereon,and the mandrel may then be mounted in a suitable machine for machiningor grinding the outer surface of the bearing elements. The machining orgrinding operation is carried out with reference to the outer surface ofthe mandrel so as to assure exact concentricity between the innersurface of the bearing elements and the outer surface of the hearingelements for proper operation when assembled in the machinery intended.For the manufacture of cylindrical bearings, i.e., bushings, anelongated cylindrical rod can be used as the mandrel whereas for themanufacture of spherical bearings, ball joints or the like, the mandrelcan consist of the ball element of the desired bearing, such ballelements being suitably supported for feed into the machine between theforming dies.

The method and operation, as generally above-described, provides anextremely economical and efficient manner of forming bearing elements.At the same time, the method and apparatus are extremely versatile informing different types of annular hearings or the like for differentoperational purposes. Proper dimensions and shapes are maintained, aswell as necessary concentricity and other design parameters. Such methodand apparatus further permits the use of low friction linings on thehearing elements, where such low friction linings are desirable in thefinal assembly and operation of the bearing structure. Considerablesavings in time, cost and labor are easily affected with a simple anduncomplicated apparatus and method.

These and other advantages will become more apparent as the descriptionproceeds, having reference to the drawings in which:

FIGURE 1 is an elevational view of a portion of a machine embodying theinvention, illustrating the position of the various parts prior to theinitiation of the method;

FIGURE 2 is a cross-sectional view of a part of the machine illustratedin FIGURE 1, taken substantially along the line 2-2 of FIGURE 1, andlooking in the direction of the arrows;

FIGURE 3 is a perspective view of one end of the strip from which thebearing blanks are formed;

FIGURE 4 is a partial elevational view of the machine illustrated inFIGURES 1 and 2, showing the machine in one position;

FIGURE 5 is a perspective view of a bearing blank;

FIGURE 6 is a partial elevational view of the machine illustrated inFIGURES 1 and 2, illustrating the various parts in a second position ofoperation;

FIGURE 7 is a partial elevational view of the machine illustrated inFIGURES l and 2, illustrating yet another position of operation;

FIGURE 8 is a perspective view of the bearing blank in the conditionillustrated in FIGURE 7;

FIGURE 9 is a partial elevational view of the machine illustrated inFIGURES 1 and 2, illustrating the parts in the final position ofoperation;

FIGURE 10 is a perspective view of the bearing blank in the conditionillustrated in FIGURE 9;

FIGURE 11 is an elevational view of the mandrel with a plurality ofbearing elements mounted thereon;

FIGURE 12 is a cross-sectional view of a bearing of compound curvaturemanufactured in accordance with the invention.

FIGURE 13 is a cross-sectional view of another form of bearing structuremanufactured in accordance with the apparatus and method illustrated inFIGURES 1 through 11;

FIGURE 14 is a cross-sectional view of yet another form of the bearing,this one a ball joint, made in accordance with the invention; and

FIGURE 15 is a cross-sectional view of still another form of sphericalbearing manufactured in accordance with the method illustrated inFIGURES 1 through 11.

Referring more particularly to the drawings, FIG- URES 1 and 2 best showthe overall pertinent portions of the machine. A machine frame,indicated generally by the numeral 10, is suitably mounted on a support,such as the floor, and has movably suspended above it a platen,illustrated generally by the numeral 12. Suitable guide members 14provide for movement of the platen 12 relative to the base frame 10.Much of the machine is of wellknown construction, and the operationaldetails will be apparent to those having skill in the art.

Movably mounted relative to the machine frame 10 is a mandrel supportmember, illustrated generally by the numeral 16, having a mandrelsupport collet 18 suitably disposed therein. A cylindrical mandrel,illustrated generally by the numeral 20, is received in the collet 18and supported in the support means 16 for purposes to become hereinaftermore apparent.

Secured to the upper platen 12, and movable therewith, is an uper dieassembly, illustrated generally by the numeral 22. Upper die assembly 22includes a forming die portion 23 having a cylindrical forming surface24 disposed above the mandrel and generally vertically alignedtherewith. Upper die assembly 22 also includes a punch member 26 havinga cutting edge 28 disposed below the forming surface 24.

Below the mandrel 20 is a first lower forming die illustrated generallyby the numeral 30. Lower forming die 30 includes an arcuate formingsurface 32 and an angular forming surface 34, the purpose for which willbecome hereinafter more apparent. An outwardly directed flange 36 on thelower forming die 30 is received in a slot 38 formed in a supportmember, illustrated generally by the numeral 40, located adjacent thelower forming die 30. Lower forming die 30 is permitted limited verticalmovement relative to the machine frame 10, and is permitted suchmovement by any suitable well-known means (not shown). A post or thelike 42 supports the lower forming die 30 in its movement between upperand lower positions, as will become hereinafter more apparent.

A second lower forming die, illustrated generally by the numeral 42, isdisposed on the machine frame 10, and below the mandrel 20. Forming die42 includes an arcuate forming surface 44, and an angular formingsurface 46, for purposes to become hereinafter more apparent. A verticalflange 48 on the die 42 is received in a suitably shaped slot 50 in thefirst lower forming die 30 so that when the first lower forming die 39moves in its vertical manner, it will be properly directed between theslot 38 in the support member 40, and the slot 50 in the second lowerforming die 42 rigidly secured to the machine frame 10. The uppersurface 52 of. the flange 48 is arcuate so as to continue the arcuatesurface 32-44 when the first lower forming die 3 is in its downmostposition.

Disposed adjacent the second lower forming die 42, and to one side ofthe mandrel 20, is a support member, illustrated generally by thenumeral 54. Support member 54- has at the upper surface thereof a stripsupporting means 56 to support a metal strip, illustrated in dashed anddotted lines at 58, and which will be hereinafter more particularlydescribed. Support means 56 also includes a punching die 57 in registrywith the punch 26, and immediately below the die 57 is a slot 6'3 toreceive the punch 26 as the upper platen 12 and the upper forming dieassembly 22 move downwardly relative to the support member 54.

Disposed above the support member 40 on the opposite side of the mandrel20 is an adjustable strip stop means, illustrated generally by thenumeral 66. Strip stop means 60 includes a member 52 extending inwardlyfrom the face of the support member 40, which may he moved in ahorizontal direction by means of a set screw s4 properly locked in placeby lock nuts or the like 6%.

In describing the operation of the machine illustrated in FIGURES 1 and2, reference is best had to FIGURES 3 through 11. A strip of metal 58having a low friction material bonded to the lower surface thereof, ashereinafter described, is fed into the strip support means 56 and as theleading edge 63 reaches the punch die 57 the upper platen is lowered topunch a notch in the end of the strip 58. Such notch 78 is of inwardlyopening generally triangular shape to eventually receive a tab ofcomplementary shape. The upper platen 12 is then raised to clear thepunch 26 from the die 67, and the strip 58 is advanced to the strip stop62. At this point, the strip 58 is disposed above the mandrel 20 whichextends outwardly from the mandrel support means 16. The upper platen 12is then again moved downwardly, and the punch 26 contacts the strip 58in the punch die 57. Thus, a blank is severed from the strip 58, suchblank being illustrated generally by the numeral 72, in FIG- URE 5.

Blank 72 has the leading end 68 formed with a notch 70 as heretoforedescribed, and has at the opposite end thereof a complementarily shapedtab 74 which, since formed by the same punch as formed the notch 70,will properly fit in the notch 70 as the operation proceeds. Tab 7 is ofgenerally triangular shape, expanding outwardly from the body of theblank 72.

As the upper forming die assembly 22 continues to move downwardly, asillustrated in FIGURE 6, the arcuate forming surface 24 begins to Wrapthe blank 72 about the mandrel 29. With continued downward movement,both the upper forming die assembly 22 and the mandrel support means 16,as well as the mandrel 20, move downwardly with the platen 21. Punch 26is of course moving freely in the slot 60 formed in the right supportmember 54. Next, the leading end 68 of the blank 72 contacts the angularforming surface 34 on the first lower forming die member 30 to bedirected downwardly and inwardly. Similarly, the tab end 74 of the blank72 contacts the angular forming surface 46 on the second lower formingdie 42 to begin to move downwardly and inwardly. At this point, thefirst lower forming die 30 is in its upward position, the base thereofbeing spaced in distance away from the machine frame 10.

Continued downward movement of the upper die assembly 22 and the mandrel20 deforms the blank 27, as illustrated in FIGURES 7 and 8. The leadingend 68 of the blank 72 is disposed between the mandrel 20 and thearcuate surface 32 on the first lower forming die 34 and the tab end 74is disposed between the arcuate surface 44 of the second lower formingdie 42 and the mandrel 20. It is to be noted that the first lowerforming die member 30 is still in its upward position. Further downwardmovement causes the first lower forming die 30 to deform the leading end68 of the blank 72 into engagement with the mandrel to give it theproper configuration, and to tuck the leading end 68 between the mandrel20 and the tab 74.

The final step in the cycle is to continue downward movement of theupper forming die assembly 22, the mandrel 20, and the first lowerforming die 30, which will cause the second lower forming die 42 todeform the tab end 74 of the blank 72 into engagement with the mandrel20. At the same time, since the first lower forming die actuates beforethe lower forming die 42, the tab 74 will be fitted into the notch 70 inaligned and contiguous engagement therewith, and the two ends of theblank 72 will be properly locked. The final configuration and positionof the various parts is best illustrated in FIGURES 9 and 10. It isthere shown that the lower forming die 30 is in its down-most positionagainst the machine frame 10, and the arcuate surface 32 of the lowerforming die 30, as well as the arcuate surface 44 of the lower formingdie 42, have deformed the blank 72 completely around the mandrel 20. Atthe same time, the tab 74 has been fitted into the notch 70 to lock theblank 72 around the mandrel 20. The final cylindrical construction isillustrated in FIGURE 10.

The machine is then recycled to raise the platen 12, the upper formingdie assembly 22, and the mandrel 20, as well as the mandrel support 16,to the original position. The mandrel 20 is indexed outwardly to receivea second blank 72, and the entire cycle is repeated. After a series ofcycles, the mandrel has formed therearound a plurality of blanks 72,such as illustrated in FIGURE 11. The series of elements are spaced alight distance apart as shown.

It is highly desirable to assure that the outer surface of the bearingelements 78 disposed on the mandrel 20 will be concentric with the innersurface of the bearing elements 78. To accomplish this, the assembly,including the mandrel 20 and the bearing elements 78, may be transportedto a suitable machine, such as a centerless grinder. Since the blanks 72have been formed to the outer surface of the mandrel, the inner surfacesof the blanks will be concentric with the outer surface of the mandrel.By grinding or otherwise machining the outer surfaces of the bearingelements 78 with reference to the outer surface of the mandrel 20, andthus will be concentric With the inner surfaces of the bearing elements.Following such grinding or machining operation, the hearing elements 78may be stripped from the mandrel 20 for installation in the desiredmachine elements.

The inner surfaces of the bearing elements are provided with a layer oflow friction material in order to provide the lubricity for the bearingassembly upon its completion. Such low friction material may take anysuitable form. However, it is preferred that such material includefibers of low friction organic polymeric material, such as Teflon, in amatrix of thermosetting resin, and more particularly, it is preferredthat the material be a. cloth formed of the low friction fibers andbonded by a thermosetting resin, such as phenolic resin, to the innersurface of the bearing element. Such Teflon cloth lined bearings arecovered by Patents Nos. 2,885,248 and Re. 24,765 in the name of CharlesS. White. The low friction material can be bonded to the strip 58 priorto the forming operation. Where the Teflon cloth is bonded to the stripby a phenolic or other thermosetting resin, the resin can be applied tothe strip and back of the cloth in liquid form, i.e., in the A stage,and, with the cloth thus bonded to the strip 58, then heatedsufiiciently to remove volatiles and polymerize the thermosetting resinto the B stage. In its B stage condition the resin is solid but is stillthermoplastic and flexible and relatively soft such that the strip canbe bent without cracking the resin layer.

With the resin in the B stage, the strip 58 is fed into the machine andcut into blanks 72 and formed about the mandrel 20 in theabove-described manner. Following the several cycles of the machine, themandrel 20 with the blanks 78 mounted thereon, and having the lowfriction material 80 between the bearing element 78 and the mandrel 20,may be conveyed to a curing oven where the phenolic resin bonding layeris cured to hardened thermoset condition, i.e., to the C stage.Following this operation, the mandrel and bearing element assembly maybe transported to a machining or grinding operation to obtain thedesired concentricity.

Particularly where thermosetting resin is used in, or as the bondinglayer for, the low friction liner, the material of which the mandrel 20is constructed is of importance in that during curing of the resin it isdesirable that not only heat but also pressure be applied. With thebearing on the mandrel during curing, the thermal expansion of themandrel, as the heat is applied, can provide the desired pressure. Asteel mandrel is excellent for most purposes; however, where a higherpressure during cure is desired an aluminum mandrel can be utilizedbecause of its higher thermal expansion rate.

Since, in the forming process of the bearing elements, the tab 74 isfitted into the notch 70, the manner in which the punch 26 engages thematerial is important. It is known that when a punch severs sheet metalin such manner, one surface of the metal at the severed end will besmooth and the opposite surface will be rough or burred. The opposite istrue of the part severed. In this instance, it is preferred that thelower edge of the tab be smooth and the upper edge surface of the notchbe smooth to ease the entry of the tab into the notch. If the method ofassembly were the opposite; that is, if the notch were to be formed overthe tab, the lower edge of the notch should be smooth and the upper edgesurface of the tab should be smooth.

The foregoing description has been related to a bearing element that iscylindrical, both on its inner surface and on its outer surface.However, the method and apparatus may be modified in order to provide abearing element of spherical or other compound curvature. For example,and with reference to FIGURE 12, a thrust bearing having a compoundcurvature and made in accordance with the invention is illustrated. Aninner bearing element of compound curvature, illustrated generally bythe numeral 82, is provided with a bore 84 to receive a suitable machineelement. An outer structure, illustrated by the numeral 86, surroundsthe ball 82, element 86 being a resilient rubber or other elastomericmember bonded to element 88 and useful for mounting the bearing in thesuspension system of an automobile to provide shock absorption. It isobvious that the bearing element, illustrated generally by the numeral88, must have an inner surface 90 of compound curvature in order toconform to the inner bearing elemnt 82. This may be accomplished in the'aforedescribed apparatus and method by providing a series of elements82 in spaced array on a mandrel, illustrated by dashed and dotted lines92. A low friction lined metal strip is then bent around each element,as described above with reference to FIG- URE 19 though in this instancethe metal strip, as it is bent around the element 82, is deformed tocompound curvature to conform to the curvature of element 82. The shapeof the forming surfaces 23, 32 and 44 of the forming die members are, ofcourse, modified accordingly. That is, instead of being of cylindricalshape they are of compound curvature to cause the strip to conform tothe curvature of element 82 as the strip is wrapped therearound. Thebearing element 88 is provided with a tab 96 properly seated in a notch98 to maintain the annular shape of the bearing member. The bearing canhave a non-spherical compound curvature, for example, a barrel shape,and hence serve to allow rotation of element 82 within bearing element88 and with the bearing being capable of taking a thrust load in thedirection of the longitudinal axis of the bore in the element 82. Thebearing can, of course, be spherical if desired to enable universalmovement between the bearing elements. After the element 88 is formedaround the inner element 82 and the resin of the low friction linercured, as described above, the annulus of rubber 86 can be bonded to theouter surface of element 88.

Reference to FIGURE 13 illustrates a use of a bearing element, such asillustrated in FIGURE 10. The bearing element 78 has a low frictionmaterial 80 bonded there to and is received in an outer housing 100.Bearing element 78 may receive a suitable shaft or the like in theinterior thereof. The tab 74 is properly seated in the notch 70 tomaintain the annular shape of the bearing element 78.

Still another bearing installation is illustrated in FIG- URE 14 whereina spherical ball andsocket joint is provided. A ball member 102 has aball portion 104 and a threaded stud 106 extending therefrom, thethreaded stud permitting mounting of the assembly in a suitable machineelement. An outer sheet metal housing, illustrated generally by thenumeral 108, includes a first cup member 1.10 and a second cup member112, each having outwardly directed flanges 114 and 116, respectively.The flanges are secured together by rivets or the like 118. A sphericalbearing element 120 comprising a metal strip having a low friction lineris formed around the ball 104 in the manner heretofore described, thebearing element 120 having a tab 124 suitably received in a notch 126.The element .120 is secured in fixed engagement to the housing 108. Withthis type of construction, a universal ball and socket joint is easilyand simply provided.

FIGURE illustrates a typical rod end type joint wherein a rod andmember, illustrated generally by the numeral 130, is provided with abanjo portion 132 and a stud portion 134. The banjo portion 132 isprovided with a cylindrical inner bore 136 to receive the bearingelement, illustrated generally by the number 138. Bearing element 138 inturn receives a truncated spherical ball, illustrated generally by thenumeral 140. In this instance, it will be noted that the bearing element138 has a spherical inner surface 142 conformed to the spherical surfaceof the ball 140 and a cylindrical outer surface 144 which is of the sameconfiguration as the cylindrical bore 136 in the banjo 132.

The formation of the bearing element 138 is according to the previouslydescribed method and apparatus for forming the spherical bearing ofFIGURES 12 or 14. Under such condition, the outer surface of thespherical bearing element must be machined to provide the cy-lindricalsurface 144. Removal of material at the crown of the spherical bearingelement would decrease the thickelement 138 toward the edges where thethickness of the element is not as greatly reduced during the machiningoperation.

Thus, a method and apparatus for forming a bearing element are providedwhich are extremely simple in operation, and which permits aconsiderable saving in time, cost and labor over prior art methods andapparatus. The wide versatility of the method and apparatus makes thesame adaptable to many different bearing structures.

Numerous changes and modifications in both the method and the apparatuswill occur to those having skill in the art after having had referenceto the foregoing description and drawings. However, it is not intendedto limit the method and apparatus of the invention by the descriptionand drawings, but by the scope of the appended claims in which:

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A method for manufacturing a bearing comprising the steps of forminga blank with complementary locking means at opposite ends thereof,wrapping the central portion of said blank against an annular surface ofa member to form said central portion to arcuate shape, wrapping one ofsaid ends of said blank against said surface to form said end to arcuateshape, and thereafter wrapping the other of said ends of said blankagainst said surface to form said other of said ends to arcuate shapeand to mate said locking means in aligned contiguous locked engagementwith each other.

2. A method as set forth in claim 1 wherein said blank is an elongatedstrip of metal having a low friction facing bonded thereto by athermosetting resin, said thermosetting resin being in a thermoplasticrelatively soft condition while said portions of said blank are formedto arcuate shape and being cured to hardened thermoset condition byheating the assembly of said member with said blank wrapped therearoundwhereby the thermal expansion of said member applies pressure to saidthermosetting resin during the curing thereof.

3. A met-bod as set forth in claim 2, wherein said member is of a metalwhich has a higher coefficient of thermal expansion than that of themetal of said blank.

4. A method as set forth in claim 1 wherein said member has a surface ofcompound curvature against which said blank portions are formed toconform to the curvature thereof.

5. A method as set forth in claim 4 wherein said surface of said memberis of spherical curvature.

6. A method as set forth in claim 1, wherein said complementary lockingmeans comprises a tab at the end of said blank which is last formed toarcuate shape and a notch in the end of said blank which is earlierformed to arcuate shape.

7. A method for making a bearing comprising wrapping an elongated metalstrip around a bearing element having an annular surface of compoundcurvature to bend said strip along its longitudinal axis into anannulus, said annulus being of compound curvature conforming to saidsurface of said bearing element.

8. A method as set forth in claim 7 wherein said elongated strip isinitially fiat and is simultaneously bent about two axes of curvature atright angles to each other when wrapped around said element.

9. A method as set forth in claim 8 wherein said strip has acomplementary locking means at the opposite ends thereof, saidcomplementary locking means being engaged with each other after saidstrip is wrapped around said bearing element to thereby secure saidannulus around said element.

10. A method as set forth in claim 8 wherein said blank comprises ametal strip having a facing of low friction material which engages saidbearing element when said blank is wrapped therearound.

11. A method as set forth in claim 10 wherein said facing of lowfriction material is bonded to said metal strip by a thermosettingresin, said resin being in a thermoplastic relatively soft conditionwhile said blank is wrapped around said bearing element and being curedto hardened thermoset condition after said blank is wrapped around saidelement.

12. A method as set forth in claim 8 wherein said surface of compoundcurvature is a spherical surface.

13. A method as set forth in claim 8 and including the additional stepof machining the outer surface of said annulus to cylindrical shapeafter said locking means are engaged with each other.

14. A method as set forth in claim 8 and including the additional stepof positioning and locking said annulus in fixed position within anouter annular member.

15. A method of making bearings comprising the steps of placing a memberhaving an annular outer surface between first, second and third formingdies, placing an elongated blank between said first die and said member,moving said first die relative to Said member to deform the center ofsaid blank against and into conformity with the surface of said member,moving said first die and said member relative to said second die todeform one end of said blank against and into conformity with thesurface of said member, and moving said first die and said memberrelative to said third die to deform the other end of said blank againstand into conformity with the surface of said member thereby to form saidblank into an annulus around and conforming to the curvature of saidmember.

16. A method as set forth in claim 15 wherein said blank is formed withcomplementary locking means at opposite ends thereof, said locking meansbeing brought into locking engagement with each other as saidlast-mentioned end of said blank is deformed against said member.

17. A method as set forth in claim 16 wherein at least one of saidcomplementary locking means is formed in said blank after said blank ispositioned between said first die and said member.

18. A method as set forth in claim 17 wherein said locking meanscomprise a tab at one end of said blank and a notch at the other end ofsaid blank, said tab being formed in said blank after said blank ispositioned between said first die and said member.

19. A method as set forth in claim 15 wherein said member has an annularsurface of compound curvature and wherein said die members have surfacesof compound curvature which engage said blank to thereby cause saidcenter portion and said ends of said blank to deform to compoundcurvature conforming to the compound curvature of said member.

20. A method of making bearings comprising the steps of bonding a lowfriction material to one surface of a metal strip, cutting said stripinto a plurality of blanks having complementary locking means at theopposite ends thereof; forming said blanks into anuli in axially spacedarray around an elongated mandrel, the locking means at the oppositeends of each of said annuli being brought into engagement with eachother during said forming, and machining the outer surfaces of saidannuli while on said mandrel to be concentric with said mandrel.

21. A method as set forth in claim 20 wherein said elongated mandrelcomprises a rod having a plurality of spaced annular members of compoundouter curvature therearound, and wherein each of said blanks is formedaround one of said annular members.

22. A method of making bearings comprising the steps of forming a firstblank to have complementary locking means at the opposite ends thereof,forming said first blank around an elongated mandrel and engaging saidlocking means with each other, forming a second blank to havecomplementary locking means at the opposite ends thereof, forming saidsecond blank around said mandrel axially spaced from said first blankand engaging said locking means of said second blank with each other,and machining the outer surfaces of said first and second blanks whileon said mandrel to be concentric with the surface of said mandrel.

23. A machine for making bearings comprising a mandrel, means forsupporting said mandrel, a first forming die for forming a centralportion of an elongated blank around said mandrel, a second forming diefor forming one end of the blank around said mandrel, and a thirdforming die for forming the other end of the blank around said mandrel,said forming dies being operated in timed relation such that one end ofthe blank is formed around said mandrel before the other end of theblank is formed around said mandrel.

24. A machine as set forth in claim 23 wherein said mandrel includes anenlargement of compound curvature around which said blank is formed.

25. A machine for making bearings comprising a mandrel, means forsupporting said mandrel, means for supporting a strip of bearingmaterial adjacent said mandrel, means for cutting the strip of materialsuch that a portion of the strip of material extends on either side ofsaid mandrel, a first forming die disposed on the opposite side of theportion of the strip of material from said mandrel, said first formingdie being movable toward said mandrel for forming the central portion ofthe strip partially around said mandrel, a second forming die forforming one end portion of the strip around said mandrel, and a thirdforming die for forming the other end portion of the strip around saidmandrel, said third forming die operating after said second forming die.

26. A machine as set forth in claim 25 wherein said means for cuttingthe strip of material is formed to cut a tab at one end of the portionof the strip and a complementary notch at the other end of the portionof the stri whereby each portion cut from the strip is provided withcomplementary locking means at the opposite ends thereof.

27. .A machine for making bearings comprising a mandrel, means forsupporting said mandrel, means for supporting an elongated strip ofmaterial such that a portion of said strip extends across said mandrel,means for cutting said portion of said strip from said strip, a firstforming die for forming said portion of said strip partially around saidmandrel, and second and third forming dies for forming the ends of saidportion of said strip around said mandrel, said second forming dieoperating in timed relation prior to said third forming die.

28. A machine as set forth in claim 27 wherein said means for cuttingsaid portion of said strip from said strip is formed to cutcomplementary locking means at opposite ends of said portion of saidstrip, and wherein the timed operation of said second and third formingdies causes said locking means to engage.

29. A machine as set forth in claim 27 and further including means forprogressively advancing said mandrel along an axial path transverse tosaid strip to permit forming a plurality of portions from said strip inspaced array along said mandrel.

30. A machine as set forth in claim 27 and further including means forprogressively advancing said strip across said mandrel as said mandrelis advanced.

31. A machine as set forth in claim 29 wherein said mandrel has aplurality of spaced annular members of compound curvature around whichsaid portions of said strip are formed.

References Cited UNITED STATES PATENTS 1,760,558 5/ 1930 Klocke 29149.52,283,918 5/1942 Dekome 29-149.5 3,220,093 11/ 1965 White. 3,237,2783/1966 White. 3,238,601 3/1966 White.

THOMAS H. EAGER, Primary Examiner.

US. Cl. X.R.

